Ioversol is disclosed as a useful nonionic x-ray contrast agent in U.S. Pat. No. 4,396,598. 5-acetoxy-acetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalam ide having the following structure: ##STR1## is an intermediate compound in the production of ioversol. The compound of Formula I and its use in the production of ioversol is likewise disclosed in U.S. Pat. No. 4,396,598 incorporated herein by reference. 5-acetoxyacetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalami de, as disclosed in U.S. Pat. No. 4,396,598, may be produced by adding acetoxyacetylchloride (AAC) to a N,N-dimethylacetamide and 1,1,2-trichloroethane solution of a compound of the following structure: ##STR2## and stirring until the reaction is complete. The reaction mixture is then diluted with 1,1,2-trichloroethane and extracted with aqueous sodium bicarbonate solutions and aqueous sodium chloride solutions.
The dilution procedure using 1,1,2 trichloroethane may alternatively be carried out using an organic solvent such as, but not 1 limited to, carbon tetrachloride, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethylene, 1,1,2-trichloroethane, 1,1,1-trichloroethane and tetrachloroethylene, but most preferably 1,1,2trichloroethane.
The procedure for producing 5-acetooxyacetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalam ide has become well known in the art and heretofore required the use of a 100% excess of acetoxyacetylchloride (AAC) to perform the intermediate synthetic step just described.
An improved procedure that minimizes the need for acetoxyacetylchloride (AAC) in the intermediate synthetic step which produces 5-acetoxyacetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalami de is desired as an alternate and more cost efficient method of producing ioversol. It is, therefore, an object of the present invention to meet these needs.